볼나사 너트부의 부하분포와 강성에 관한 연구

초록

Ball screws are widely used in precision machinery. Positioning accuracy of precision machines depends upon stiffness of ballscrews and lead errors of the ball screw mechanism. The lead errors are controlled by proper selection of ball screw grade according to the design requirement. By the way, the stiffness is composed of the nut, screw shaft, nut bracket, and support bearing stiffnesses. As the nut stiffness are function of ball, grooves, contact mechanism, preload and loading conditions, it is difficult to estimate the nut stiffness in the design process of precision machinery. In this paper, to make a nut stiffness estimator applicable to design of precision machinery, load distribution analysis including Hertzian contact deformation and manufacturing errors is studied for various load and assembly conditions. It is confirmed that developed explicit stiffness model is applicable to predict positioning accuracy of ball screw mechanisms through case studies.

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